High-resolution microCT reveals relationships between stomata and interior leaf anatomy in Sorghum

Abstract

Abstract Stomata are pores in the leaf epidermis that regulate the trade-off between CO 2 uptake for photosynthesis and water vapor loss to the atmosphere. Stomatal patterning therefore influences water use efficiency and is a target for engineering to avoid drought stress. However, there is limited understanding of how internal leaf anatomy is coordinated with stomatal development, in part due to the technical challenges of assessing three-dimensional anatomy with sufficient resolution. C4 grasses are understudied, and this is a significant knowledge gap given their file-like stomatal distribution and unique mesophyll organization. In this study, wild-type sorghum and a low-stomatal density transgenic line expressing a synthetic Epidermal Patterning Factor (EPF syn ) were studied. High-resolution microCT was paired with machine learning to characterize three-dimensional traits of mesophyll, epidermis, and airspace, which together determine g ias . Sorghum internal leaf airspace is an arrangement of large sub-stomatal airspaces with thin air passageways. Adaxial and abaxial surfaces differed in stomatal patterning relative to mesophyll structures, sub-stomatal crypts and airspace CO 2 conductance (g ias ). Surprisingly, adaxial stomata were consistently located above rather than between vascular bundles. Unexpectedly, g ias was not significantly different in wild-type versus EPF syn . EPF syn plants had larger crypts and shifts in internal leaf anatomy, indicating a potential compensation mechanism for predicted impacts of reduced stomatal density on g ias . These findings provide a new understanding of the interplay between leaf surface specific anatomy and internal structural patterning of the mesophyll in a C4 species, and provides knowledge relevant to engineering water use efficiency in crop species.

Affiliated Institutions

• University of Illinois Urbana-Champaign US
• Yale University US
• National Bioproducts Institute (South Africa) ZA
• Biopterre CA

Related Publications